Wednesday, 30 September 2015

Burmargiolestes cf. laidlawi

Last weekend I wanted to escape the gloom of Hanoi and flew down to Da Nang, from where I went to the area around P'rao along the Ho Chi Minh Highway in Quang Nam Province. This is quite an interesting area with some reasonable remaining forest and a few interesting streams. It was here that I trotted through a stream for two consecutive days, during which I added a few species to my Vietnamese list. It was a bit cheeky, as this is outside my normal area of research (too far south), but it provided a lot of interesting insights. Anyway, on the second day I was searching for the female of an as yet, presumably, undescribed Coeliccia species when I noticed on a very wet slope just above the stream a Burmargiolestes male hiding amongst the roots. Interestingly, it did not have the whitish rings at the tip of the abdomen of B. melanothorax and it also seemed to have rather extensive pale sutures on the thorax. I was able to catch it and in hand noticed an additional and exciting feature. It had a pale blue face! Now, B. melanothorax (and rather similar Argiomorpha fusca) has an ochre face. This clearly was something else. Checking the literature at home it dawned that the species described as B. melanothorax by Selys and illustrated in Fraser (1933) had been shown by Lieftinck (1960) and Asahina (1985) to be a different species, B. Laidlawi, that differed for instance in the pale blue face. This species occurs in India.

Rory Dow alerted me to the fact that similar specimens had been recorded in Vietnam before. Actually from Bach Ma National Park, close to Da Nang, by Matti Hamalainen. And Haruki Karube also mentioned having recorded it. So in the south of Vietnam there is a species with a pale blue face and mine is not just an aberration.

Interestingly, the description in Fraser mentioned that the pale blue extends to the base of the antennae, exactly like in my specimen (the ochre of B. melanothorax extends only marginally unto the frons). Rory mentioned that there are some small differences between the specimens of B. laidlawi from India and those from around Da Nang, for instance by displaying a pale area on S9. This is mentioned also by Asahina. However, the description by Fraser mentions only "Abdomen glossy black or blackish-brown in subteneral specimens, segments 3 to 6 with an obscure yellowish spot or annual near the base." He says noting about a pale area on S9. I have not been able to find any photo or further useful illustration of the species and therefore think it is perfectly possible that the species in Vietnam is in fact B. laidlawi. Nevertheless, given the long distance between it known range and Vietnam, it is better to consider this B. cf. laidlawi until a direct comparison with Indian laidlawi is possible. 

Male Burmargiolestes cf. laidlawi. Note the pale lateral lines on the prothorax, the pale line at the dorsal end of the thoracic sutures and the all dark S8-10. 
Slightly overexposed face of the same male. The pale blue extends well beyond the base of the antennae and up to the central ocellus. This is much more extensive than in B. melanothorax.

Tuesday, 29 September 2015

The real female Planaeschna tomokunii

On September 24 I went to Tam Dao to look for Planaeschna tamdaoensis and P. tomokunii. The first I wanted to catch to see if it is truly different from P. gressitti, and the other to verify what I had concluded was P. tomokunii from Pia Oac and Yen Bai. The day started dismally. It was misty and the road to Tam Dao 2 was blocked. So I went to the stairway to the antenna above Tam Dao. This is the location where Cuong had caught the species before and I was hoping that I might see it at a small stream in the forest there. Previously I had not been lucky, but this time, after some staking out, I noticed a female searching for a place to oviposit. I could not reach her, but several other specimens made an appearance and eventually I could net one. This is a remarkably robust species at 71mm body length. And even if I could not find a male, this female as enough to show that the drawings and description of Cuong are very accurate. It also made clear that this species is certainly not identical to what occurs at Pia Oac and at Yen Bai. It is of course still possible that the males are variants of the same species, but I for sure had no similar females yet. Whatever the females from Yen Bai and Pia Oac (at least two different species) are, they are not P. tomokunii. I hope that soon I will have time to try for the male again.

Planaeschna tomokunii, remarkably robust and with relatively dark abdomen.

Its face is not as bland pale brown as in most. The labrum is distinctly pale and there are clear  brown flecks on the postclypeus.
The pattern on S2 is very interesting. The dorsal line is indeed interrupted, and the distal mark is quite narrow

Monday, 7 September 2015

Anax parthenope julius - confirmed

Karube recorded Anax parthenope julius from Tam Dao in September 1990. Sebastien Delonglee recorded quite a few in September from Cat Ba Island. And I had seen some specimens in the field both in spring and autumn that seemed good candidates. But I had never been able to verify the species of sure. Until yesterday, when I decided to drive to Xuan Son and checked a large lotus pond in the hills along the QL32. There were several Anax cruising around and they looked smallish and had brownish abdomens. The looked like good candidates for Anax parthenope julius and when I finally caught one: yes, it was. Almost continuous pale line over the abdomen, facial pattern, pattern on the frons, very short epiproct. Coolio!
Have not yet seen A. immaculifrons, which is known from Central Vietnam, nor A. panybeus, which might occur, given its distribution both to the north and to the southwest of Vietnam. But it has not been recorded yet, although it is not that difficult to recognize when seen well. Yet another Anax is A. nigrofasciatus, a common mountain species.

Male A. parthenope julius, with extensive pale markings on brownish abdomen, reddish femora. A nice dragonfly.

The frons in dorsal view, with black cross bar bordered by pale blue

Seen from the front the frons has a clear horizontal black field. The brown spot on the postclypeus is an aberration.

The appendages in dorsal view. Note the very short and rounded epiproct.


Friday, 4 September 2015

Chlorogomphidae - just beautiful

Over these 2 years I have been lucky enough to encounter many species from the Chlorogomphidae. A tip of the Iceberg, but I am not complaining. Almost all are spring species, with a few lingering on into early summer. This year I caught up with a species that earlier I had failed to see, although I went looking for it in Cao Bang Province in an area where it is not uncommon. This was magical Chlorogomphus papilio. There are actually quite a few Chlorogomphids with colorful wings, but this species stands out. In most species it is the female that has colorful wings, but in C. papilio it is the male that is wonderfully striking. It inhabits medium-sized streams with some rocks and I have encountered it at least at 4 different sites scattered around the province.

This is one of the first specimens I observed. I had already seen it the evening before, hunting high over the forest, but the second day could take a few photos of it. Even at long distance with a telephoto lens it is recognizable! I was so very excited. In fact, at a distance the translucent parts are difficult to see and it truly looks like a butterfly.
This is another male in hand. They have quite a slow and deliberate flight when patrolling.

Scan of a male in dorsal view. Luckily this species is not all that rare, although the river systems it inhabits are vulnerable to all sorts of pollution.

 Another magnificent species is C. auratus. This species was considered near-threatened according to IUCN, because of the scarcity of records, although it had been found at Tam Dao and in Central Lao PDR. It is however one of the commoner species and I have seen it in Yen Bai Province, in Cao Bang Province, in Lang Son Province and in Ninh Binh Province, and sometimes in surprisingly disturbed areas. The female has beautifully colored wings.

A female posed in Cuc Phuong, where it co-occurs with C. nakamurai, although much less common
In this dorsal view scan of a female the golden-brown wings with dark-brown tips are more obvious.
And the last colorful-winged species I would like to introduce here is female C. nakamurai. This female is very similar in wing-pattern to C. albomarginatus, but is a shade lighter and has dark wingtips. Apparently this species is also known from former Ha Tay Province, but I do not know the location of Mount Tan Vien. The only well established population seems to be in Cuc Phuong National Park, where it is in fact surprisingly common in the few available shallow streams. But water availability is low in the forest, so in absolute numbers it is certainly not abundant. Males patrol incessantly, but females drop down from the canopy and then flutter in dark shady places close to the surface. They keep on moving about while ovipositing left and right and are not easy to take pictures of in their dark surroundings.

A female fluttering low over leaf litter in the dark. Compare the female of C. albomarginatus, a mountain species, on Sebastian's blog.

An old female in dorsal view. Note the dark wingtips and brown, not black coloring.

Wednesday, 2 September 2015

Petaliaeschna tomokunii - the other Petaliaeschna

Haruki Karube described Petaliaeschna tomokunii in 2000 from Pia Oac in Cao Bang Province. Superficially this is a species very similar to P. flavipes. Indeed, it is easily overlooked as this species. I had observed P. flavipes both in Yen Bai Province and at Pia Oac. This year I carefully checked specimens at these sites and found that P. tomokunii flies at exactly the same places, although it appears to prefer the late afternoon, rather than the evening. I caught them both at Pia Oac and at Yen Bai patrolling over puddles on trails. In hand they are basically similar to P. flavipes, but the male has pointed rather than blunt appendages, making it easy to identify in hand. There luckily is another difference. P. tomokunii has the complete face and frons yellow-orange. In P. flavipes the upper edge of the antefrons is darker and the postfrons has a vague dark T-spot. This allows the females to be separated in hand too.
This is a spring species, like P. flavipes. I observed it between May 14 and June 29.

Male of Petaliaeschna tomokunii. Very similar to P. flavipes

But the appendages are quite different, both in dorsal view, as here, and in lateral view (see below). They are decidedly pointed.
This is the lateral view (not so sharp, sorry) 
And this is the all-yellow face and frons

A scan of a female in dorsal view, showing the unmarked frons